Auto Bravado's ideas on the the Trucks or Cars Miles per Gallon: We all want better numbers, but do we really know how to get them? Let us learn that to get results is to have fun! There are tricks that it took many mechanics decades of experience to figure out and perfect.

Saturday, February 25, 2017

VVT-i, or Variable Valve Timing with Intelligence is Toyota's name for the subject at hand. Other manufacturers have other
names for it.

Now, what's really fun, is that all
modern cars having timing advanced adjustments on the fly, but being
able to adjust the timing of when valves actually open and close is
revolutionary for the time if you ask me.

Timing advanced, more fully explained,
then what's in the video: spark timing, or timing advanced, can be
changed at the flick of PCM's choice to generate more power. Under
heavier loads, you can't have as much timing advance, or you get
knock.

Timing advance is just a related point
however. With VVT-i, changing when the intakes open and close was
added more as a way to lower emissions, then it was to gain that much
power. It really only gives like 5 points of bHP, or horse power at
the crankshaft, and even less, only a few horsepower at the wheels. When it
advances when the intakes open, it actually doesn't let the engine
draw in as much fuel and air. This makes idling these cars much more
efficient then their predecessor. This engine concept has been around
since the 19th century, but only now can we have a more
efficient engine AND a more powerful engine at the same time.

The other reason for better emissions however, is that a later intake means that the exhaust doesn't escape as well so it can be Toyota's way of not having an EGR system. The inert gases reduce combustion temperatures, decrease NOx, if this the example engine even is capable of making NOx, I'd be surprised, but these are the normal functions of EGR. On bigger, badder engines, without EGR, you'll pit your pistons, so let's not just hate the fact that they can clog up or make our intakes dirty. They have a valuable purpose for engine longevity as well!

And now to the YouTube segment today of our article!

Shown by a Toyota Corolla 1998-1999 vs
2000-2002 Engine - Chevy Prizms are the "same" except for
these changes across those 2 year zones. What's really interesting,
is this engine has a design change but it's the "same" car
from 1998 to 2002. It's all the 8th generation of Corolla.